If the number of rockets launched globally increases as predicted, the still-healing ozone layer could be under attack again.

Scientists have predicted that the hole in the ozone layer — caused by substances once used in refrigerants and aerosols — will close permanently in 50 or 60 years, thanks to the 1987 Montreal Protocol, which banned the most-destructive chemicals.

Many smaller sources of ozone depletion — including rockets — were known in the 1980s, but ignored in the face of the larger problem. But now, as countries around the world make plans to use more rockets, whether for communication satellites or missions to Mars, it’s time to revisit the damage rockets could have on the thin layer of ozone protecting Earth from a barrage of ultraviolet rays, according to a University of Colorado atmospheric scientist.

“It’s probably time to take this issue more seriously,” said Darin Toohey, a professor in CU’s Department of Atmospheric and Oceanic Sciences. “It’s not that people haven’t thought about it, but wethought, ‘It’s a small depleter and therefore not anything we really need to worry about.'”

Along with Martin Ross, who works at The Aerospace Corporation in Los Angeles, Toohey published a new study this week in the journal Astropolitics, which examines whether the rocket industry should be more regulated in the future.

As large-scale schemes to cool the Earth in the face of global warming — “geoenginering” ideas such as injecting sulfates in the upper atmosphere or sending sunshades into space — gain more traction, the ozone question deserves more consideration, Toohey said, since many of the plans would require a fleet of rockets.

Unlike chlorofluorocarbons, the ozone-eating chemicals found in old aerosol cans and air conditioners that stick around in the atmosphere for many decades, rockets only destroy the ozone layer as they punch through it on their way into space.

That’s good news when it comes to controlling ozone damage.

“We can stop launching rockets anytime we want,” Toohey said.

The study does not advocate for any particular policy, but it does suggest that it might be time to learn more about how much different rockets destroy ozone under different circumstances, a proposition Toohey says would be relatively cheap.

Dave Fahey, one of many researchers at the National Oceanic and Atmospheric Administration in Boulder involved with the Montreal Protocol, is more concerned about the aggregate effect of all the small ozone depleters, including rockets, that are not regulated

“There’s a number of exemptions to the protocol,” he said. “Each one by itself is small, but if you go too far, it could be death by a thousand cuts.”

Contact Camera Staff Writer Laura Snider at 303-473-1327 or sniderl@dailycamera.com.

This was a study that advocates for another study. If I were still in the study business, I would certainly argue the same conclusion.

I like the hypothesis: rockets “punch holes” in the ozone layer as they travel through it. Probably no chance that the gaseous ozone layer simply refills in the vacuum immediately behind the rocket.

slehan@aupairint.com

4/3/2009 9:31:51 AM